1. Field of the Invention
This invention relates to a clutch.
2. Prior Art
The type of clutches with which the present invention is concerned are used, for example, in an apparatus for automatically fastening an electrical terminal to an end of a length of wire. One such conventional clutch shown in FIGS. 1 and 2 comprises an outer clutch member 10 of a cylindrical shape connected to a drive means (not shown), an inner clutch member 11 of a cylindrical shape fixedly secured by a key 12 to a shaft 13 connected to a load (not shown), and a bushing 14 mounted on the inner clutch member 11 and supporting a plurality of rollers 15 interposed between the inner and outer clutch members 11 and 10. A spring 16 extends between a pin 17 secured to the inner clutch member 11 and a screw 18 threaded into the bushing 14 to urge the bushing 14 to angularly move in a clockwise direction (FIG. 2) about the axis of the shaft 13. The bushing 14 is held in its inoperative position (FIG. 2) by a keeper means (not shown) against angular movement.
The operation of this conventional clutch will be described with reference to FIGS. 3 and 4.
When the bushing 14 is held in its inoperative position, each roller 15 is not clamped or locked by the inner and outer clutch members 11 and 10, as shown in FIG. 3, since each roller 15 is disposed at a respective one of flat portions on the outer circumferential surface of the inner clutch member 11. In this condition, when the drive means drives the outer clutch member 10 to rotate in a clockwise direction, the rotation of the outer clutch member 10 is not transmitted to the inner clutch member 11. And, when the keeper means is disengaged from the bushing 14, the bushing 14 is angularly moved instantaneously at an angle A from its inoperative (FIG. 3) to operative (FIG. 4) position under the influence of the spring 16, so that each roller 15 is forced in between and brought into locking engagement with the inner and outer clutch member 11 and 10. As a result, the rotation of the outer clutch member 10 is transmitted to the inner clutch member 11. Before the outer clutch member 10 is coupled to the inner clutch member 11, the former is rotated usually at a speed of 250 rpm while the latter remains stationary. Therefore, a substantial impact is generated when the rollers 15 are brought into locking engagement with the inner and outer clutch members 11 and 10, thereby causing substantial impact and vibration. Also, when this conventional clutch is to be disengaged, the bushing 14 is brought into striking engagement with the above-mentioned keeper means with a substantial impact since the bushing is rotated at a considerable speed together with the inner and outer clutch members 11 and 10. This also produces substantial noise and vibration.